Earless clamp structures are known in the prior art, for example, as described in the U.S. Pat. No. 4,492,004 in which outwardly bent hooks in the inner band portion are adapted to engage in apertures in the outer band portion as the clamp is tightened about the object to be fastened thereby by engagement of a tool at tool-engaging abutment surfaces in the clamping band. These prior art earless clamp structures also include means to assure an internal clamping surface devoid of discontinuities, steps or gaps by the use of a tongue-like extension in the inner band portion adapted to engage in a tongue-receiving channel in the outer band portion. Tightening of the clamp structure is thereby achieved by the use of a pincer-like tool with mutually facing engaging points adapted to engage in the openings formed in substantially semi-cylindrically shaped tool-engaging embossments providing the transversely extending tool-engaging abutment surfaces in the inner and outer band portions. This U.S. Pat. No. 4,492,004 also describes the use of an approximately L-shaped preassembly hook which was subsequently improved to provide a snap-in preassembly hook arrangement as described in U.S. patent application Serial No. 06/942,694, filed Dec. 22, 1986, and entitled "Clamp Structure With Preassembly Arrangement."
The aforementioned type of earless clamp structures have proved immensely successful from a commercial point of view. To avoid the need for special pincer-like tightening tools with mutually facing points that are likely to meet with substantial wear and tear, a modified earless clamp structure has been proposed in U.S. Pat. No. 4,712,278 in which the tool-engaging surfaces for the tightening tool were so constructed and arranged by the use of bent-out tab-like members that a tool with flat surfaces could be used.
One problem that arose with all of the aforementioned types of earless clamp structures was the possibility of over-torquing the clamp during tightening thereof, i.e., excessive tightening of the clamp which could result in damage to parts of the clamp structure.